TWI638228B - Metrology methods, metrology apparatus and device manufacturing method - Google Patents

Abstract

A metrology device that uses radiation (304) in an EUV band. A first detection system (333) includes a spectral grating (312) and a detector (313) for capturing a spectrum of the EUV radiation after interaction with a target (T). The properties of the target are measured by analyzing the spectrum. The radiation (304) further includes radiation in other wavelength bands such as VUV, DUV, UV, visible light, and IR. A second detection system (352, 372, 382) is configured to receive at least a portion of the radiation (350) reflected by the first spectral grating and capture a spectrum of one or more of the other wavelength bands ( SA). The second band spectrum can be used to enhance the accuracy of the measurement based on the EUV spectrum, and/or it can be used for a different measurement. Instead of or in addition to the spectral gratings, other types of detection such as polarization may also be used.

Description

Weight measurement method, weight measurement device and device manufacturing method

The present invention relates to metrology methods and apparatus useful for device fabrication, such as by lithography, and to methods of fabricating devices using lithography. The method of measuring the critical dimension (linewidth) is described as a specific application for this weighting. Methods of measuring asymmetry related parameters such as stacking are also described.

A lithography apparatus is a machine that applies a desired pattern onto a substrate, typically applied to a target portion of the substrate. The lithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that case, a patterned device (which is alternatively referred to as a reticle or pleated reticle) can be used to create a circuit pattern to be formed on individual layers of the IC. This pattern can be transferred to a target portion (eg, including a portion of a die, a die, or a plurality of dies) on a substrate (eg, a germanium wafer).

In lithography procedures, the resulting structure needs to be measured frequently, for example, for program control and verification. Various tools for performing such measurements are known, including scanning electron microscopy (SEM), which is often used to measure critical dimensions (CD). Other specialization tools are used to measure parameters related to asymmetry. One of these parameters is a stacking (alignment accuracy of the two layers in the device). Recently, various forms of scatterometers have been developed for use in the field of lithography. These devices direct the radiation beam onto the target and measure one or more properties of the scattered radiation - for example, The intensity at a single angle of reflection that varies according to the wavelength; the intensity at one or more wavelengths that varies according to the angle of reflection; or the polarization that varies according to the angle of reflection - to obtain the attribute of interest that can be used to determine the target spectrum". The determination of the attribute of interest can be performed by various techniques: for example, reconstruction of the target structure by a repetitive approach such as tightly coupled wave analysis or finite element methods; library search; and principal component analysis. Compared to SEM technology, optical scatterometers can be used at much higher yields on a large scale or even on all product units.

A relatively large target used by conventional scatterometers, for example, 40 microns by 40 microns, and the measurement beam produces a spot that is smaller than the grating (i.e., insufficient grating fill). In order to reduce the size of the target, for example to 10 microns by 10 microns or less, for example so that it can be positioned in the product features rather than in the scribe line, a so-called "small target" metrology has been proposed in which the grating is made smaller than the spot. (ie, the grating is overfilled). These targets can be smaller than the illumination spot and can be surrounded by the product structure on the wafer. Typically small targets are used for the measurement of overlays and other performance parameters derived from the measurement of asymmetry in the grating structure. By placing the target in the product characteristics ("in-grain target"), it is expected to increase the accuracy of the measurement. For example, the accuracy of the improvement is expected because the intra-grain targets are affected by program variations in a manner more similar to product features, and smaller interpolated values may be required to determine the effects of program variations at actual feature sites. These optical measurements of the overlay target have been extremely successful in improving stacking performance in mass production. So-called dark field imaging has been used for this purpose. Examples of dark field imaging metrology are found in the International Patent Application No. US-A-200100, 328, 655 A1, the disclosure of which is incorporated herein by reference. Further developments of this technology have been described in the published patent publications US20110027704A, US20110043791A, US2011102753A1, US20120044470A, US20120123581A, US20130258310A, US20130271740A and US2015138523. Also A similar small target technique for focus performance and dose performance is implemented. The contents of all such prior applications are hereby incorporated by reference.

However, as technology evolves, performance specifications become more stringent. In addition, small target technologies have not been developed for measurement of other parameters such as line width or critical dimension (CD). Another limitation of the current method is that it is performed with optical wavelengths that are much larger than typical dimensions of actual product features. The specific parameter of interest is the line width (CD). CD weights and measures suffer from low accuracy, crosstalk between parameters of interest, and crosstalk (program robustness) between the parameters of interest and other hidden parameters. As microstructures shrink and become more complex in geometry (eg, become 3-D structures), known techniques of CD metrology strive to provide accuracy, precision, and speed. Another parameter of interest is a pair of pairs.

An attractive option for improving the measurement of smaller features would be to use radiation having a wavelength that is shorter than the wavelength used in conventional scatterometers. Radiation in a wave band called a wave band of the following: ultraviolet (UV), deep ultraviolet (DUV) radiation, vacuum UV (VUV), extreme ultraviolet (EUV), soft x-ray (SXR) and x can be used. Rays. These bands are of course simply named as areas of continuous electromagnetic spectroscopy rather than areas defined by any hard entities. The bands can be defined differently by different workers and can overlap each other.

Reflectance measurements using X-ray (GI-XRS) and extreme ultraviolet (EUV) radiation under grazing incidence are known for measuring the properties of the film and layer stack on the substrate. In the field of general reflectometry, goniometers and/or spectroscopy techniques can be applied. In goniometry, changes in the reflected beam with different angles of incidence are measured. Spectral reflectometry, on the other hand, measures the spectrum of the wavelength of reflection at a given angle (using broadband radiation). For example, EUV reflectometry has been used for the detection of reticle substrates prior to fabrication of reticle (patterned devices) for use in EUV lithography. For example, S Danylyuk et al. have been in the "Multi-angle spectroscopic EUV reflectometry" A study of these techniques is described in for analysis of thin films and interfaces" (Phys. Status Solidi C 12, 3, pp. 318-322 (2015)). However, such measurements are different from the measurement of CDs in a periodic structure. Moreover, none of these known techniques are suitable for metrology of small targets such as intra-grain gratings, particularly in view of the extremely shallow grazing incidence angles involved.

In the international patent application PCT/EP2016/056254, which is hereby incorporated by reference in its entirety, the disclosure of the disclosure of the disclosure of the disclosure of the disclosure of the disclosure of Radiation in the wavelength range from meters to about 100 nm. Spectral reflectometry is performed using radiation scattered at zero and/or high diffraction orders. Compared to the T-SAXS or GI-SAXS method, a smaller spot size is achieved using a grazing incidence angle that is higher than the grazing incidence angle that can be used at x-ray wavelengths. The diffracted signal is further enhanced by using a conical mounting between the EUV optical system and the substrate. This allows for a non-zero incident azimuth relative to the periodic direction of the target structure. The content of the prior application is hereby incorporated by reference.

These techniques of using radiation in extreme ultraviolet (EUV) bands provide specific advantages for the measurement of CDs, overlays, and other attributes of small metrology targets. Conveniently, these small metrology targets can again have the form of a periodic structure. Compared to the usual practice of optical scattering measurements, EUV rays will not be strongly affected by the underlying features, and as a result, the modeling of the periodic structure itself can be more accurate. To obtain enough information for CD weights and measures, the spectral properties across the EUV wavelength range can be measured. On the other hand, it may be beneficial to use radiation in different wavelength ranges and/or to measure the target structure using different properties of the radiation. For example, when measuring in combination with radiation in different bands in a reconstituted or similar manner, the accuracy of the calculated measurements of the attributes of interest can be improved. When using radiation in a single waveband, the cross-correlation between different material properties and/or geometries of the structure can result in errors and/or uncertainties in the calculated properties of interest. In the case of using information from additional bands, these errors can be resolved and not Determine some of the degrees. Of course, measurements made in different wavelength ranges can also be used independently to measure two different properties.

In the international patent application referred to, a form of mixed metrology is proposed in which EUV radiation is used to measure a larger target having a product-like structure, and an angular resolution scatterometry that works in a more conventional optical band is used. Measure small intragranular targets. The results of EUV measurements on several substrates are used to calibrate optical measurements in high volume manufacturing. In the European Patent Application No. 15202273.7, which is also not published in the priority date of the present invention, a weight measuring device based on EUV spectral reflectometry and an angle resolved scatterometer acting in, for example, an optical band are combined in a single device. in. The content of this European patent application is incorporated herein by reference. In these prior applications, although the devices required for measurement at different wavelength ranges were housed together and shared some common infrastructure, different measurements were made using separate sources and optical systems within the same device.

The present invention is directed to an alternative method and apparatus for determining the weight of the properties of a microstructure found in semiconductor manufacturing or elsewhere.

In a first aspect, the present invention provides a metrology apparatus for measuring an attribute of a structure, the weighting apparatus comprising: an illumination system for irradiating the structure with radiation; a first detection system a first spectral grating and a first detector configured to receive the radiation after interacting with the structure, the first detector configured to receive by the The first spectral grating diffracts one or more higher order radiation to detect a spectrum in a first wavelength band; a second detection system configured to receive zero order radiation reflected by the first spectral grating The zero-order radiation in one or more of the other bands is analyzed at least in part.

The inventors have recognized that measurement in one or more additional bands can be performed by utilizing the broadband nature of an EUV radiation source without the need to separate illumination and separate the metrology timing. In particular, the inventors have recognized that a spectral grating for analyzing the spectrum of radiation in the first band can deliver additional information about the target structure in one or more different bands. Radiation as a by-product. For example, a spectral grating can be used to obtain a spectrum of radiation in an EUV band. At the same time, the zero-order reflected radiation from the grating may contain information about the structure and, for example, longer wavelength bands of VUV, DUV, EUV, and visible light bands. In embodiments using a wideband source, spectral information for different band information can be obtained simultaneously without adding measurement time. The increase in device cost can also be extremely modest.

Reference to a wavelength range from 1 nm to 100 nm is not intended to mean that the device or method should use wavelengths across the entire wave range, or even enable this. An alternative implementation may optionally function with wavelengths that span only a subset of the range. The appropriate range will depend on the availability of the appropriate source and the size of the structure to be measured.

In a particular implementation, the metrology system includes a substrate support that is adapted to receive a semiconductor wafer (eg, a 300 mm wafer) from an automated wafer handler.

In a second aspect of the present invention, a method of measuring an attribute of a structure by a lithography process is provided, the method comprising the steps of: (a) applying radiation comprising a first band And radiating radiation in a second band to irradiate the structure; (b) directing at least a portion of the radiation after interaction with the structure to a first spectral grating; (c) using the first The spectral grating diffracts one or more high-order radiations to detect a first wave One of the bands; (d) analyzing at least a portion of the zero-order radiation reflected by the first spectral grating in the second band.

The present invention further provides a device manufacturing method comprising: transferring a pattern from a patterned device to a substrate using a lithography process, the pattern defining at least one structure; measuring one or more properties of the structure to Determining a value for one or more parameters of the lithography program; and applying a correction in subsequent operations of the lithography program based on the measured property, wherein the step of measuring the attributes of the structure includes The metrology device is used to measure an attribute in accordance with the first aspect of the invention as set forth above.

The present invention further provides a device manufacturing method comprising: transferring a pattern from a patterned device to a substrate using a lithography process, the pattern defining at least one structure; measuring one or more properties of the structure to Determining a value for one or more parameters of the lithography program; and applying a correction in subsequent operations of the lithography program based on the measured property, wherein the step of measuring the attributes of the structure includes An attribute is measured in accordance with the method of the second aspect of the invention as set forth above.

Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail herein. It should be noted that the invention is not limited to the specific embodiments described herein. These embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the art in view of the teachings herein.

200‧‧‧ lithography device LA / lithography tools

202‧‧‧Measuring station MEA

204‧‧‧Exposure Station EXP

206‧‧‧ lithography device control unit LACU

208‧‧‧ Coating device

210‧‧‧ baking device

212‧‧‧Developing device

220‧‧‧ patterned substrate

222‧‧‧Processing device/etching device

224‧‧‧Processing device/annealing device

226‧‧‧Processing device/step

230‧‧‧Substrate

232‧‧‧Substrate

234‧‧‧Substrate

240‧‧‧Mixed Weights and Measures System/Metrics

242‧‧‧Metrics and Weights / First Weights and Measures / Extreme Ultraviolet (EUV) Weights and Measures

244‧‧‧Second weight measuring device

246‧‧‧ Weights and Measures Processing System

248‧‧‧First Spectral Data

250‧‧‧Second spectrum data

252‧‧‧Measure

300‧‧‧Extreme ultraviolet (EUV) weighing and measuring device

302‧‧‧X-Y plane

304‧‧‧ incident ray

306‧‧‧Detector/plane

308‧‧‧reflecting rays

310‧‧‧Spectrum

312‧‧‧ grazing incidence diffraction grating/first spectral grating

313‧‧‧Detector

314‧‧‧Second detector/reference spectrum detector

316‧‧‧ source radiation

318‧‧‧Diffractive grating/spectral grating

320‧‧‧first-order diffraction ray/reference spectrum

330‧‧‧First source of radiation

332‧‧‧Lighting system / lighting optics

333‧‧‧First Detection System

334‧‧‧ Positioning System

336‧‧‧ movable support

340‧‧‧ processor

350‧‧‧Zero-order radiation beam/zero-order reflected radiation

352‧‧‧Second detection system

354‧‧‧Second Spectral Grating

356‧‧‧Second detector

358‧‧‧Second spectrum

360‧‧‧wavelength selection filter

362‧‧‧Analyzer

370‧‧‧zero-order reflected radiation

372‧‧‧The third detection system

380‧‧‧zero-order reflected radiation

382‧‧‧Four detection system

500‧‧‧Polarization Analyzer

502‧‧‧Detector

504‧‧‧ Wavelength selective filter

616‧‧‧Substrate support

630‧‧ ‧ pump laser

632‧‧‧High-order harmonic generation (HHG) air cells

634‧‧‧ gas supply parts

636‧‧‧Power supply

640‧‧‧First radiation beam

642‧‧‧ Beam

654‧‧‧ components

656‧‧‧ focused beam

900‧‧‧Metrics and scales

902‧‧‧ operation

904‧‧‧ first chamber

906‧‧‧ second chamber

908‧‧‧ third chamber

910‧‧‧ first window

912‧‧‧ second window

1300‧‧‧Metrics and scales

1304‧‧‧ incident ray

1307‧‧‧Sloping plane

1308‧‧‧reflecting rays

1330‧‧‧radiation source

1332‧‧‧Lighting system

1333‧‧‧First detection system

1334‧‧‧ Positioning system

1352‧‧‧Second detection system

D‧‧‧The periodic direction of the target structure

MA‧‧‧patterned device / doubling mask

MET3‧‧‧Metrics and Weights

N‧‧‧ direction

R‧‧‧Formulation Information

S‧‧‧radiation spot

S11‧‧ steps

Step S12‧‧‧

S13‧‧‧ steps

S14‧‧‧ steps

S15‧‧‧ steps

S16‧‧ steps

S17‧‧‧ steps

S18‧‧‧ steps

S19‧‧‧Steps

S20‧‧‧ steps

S21‧‧‧ steps

S22‧‧‧ steps

S23‧‧‧Steps

S24‧‧‧Steps

SA‧‧‧ extra signal

SA2‧‧‧ extra signal

SA3‧‧‧ extra signal

SCS‧‧‧Supervisory Control System

SR‧‧‧ reference spectral signal

ST‧‧‧Ultraviolet (EUV) spectral signal

T‧‧‧Metrics target/target structure/grating target

W‧‧‧Substrate/substrate support

W'‧‧‧ substrate

Embodiments of the present invention will now be described with reference to the accompanying drawings, in which: FIG. 1 depicts a lithographic apparatus along with other apparatus that form a production facility for a semiconductor device and includes an implementation in accordance with the present invention Example of a metrology device; FIG. 2 illustrates the geometry of incident and reflected rays relative to a grating target and a first detection system for performing EUV spectral reflectometry in an embodiment of the metrology device of FIG. 1; 3 schematically illustrates components of a metrology apparatus that performs the EUV metrology method of FIG. 2 and shows an added second detection system; FIG. 4 schematically illustrates a portion of the apparatus of FIG. 3, including a second detection system More details of an example and optionally include third and fourth detection systems; FIG. 5 schematically illustrates a portion of the apparatus of FIG. 3, including more details of an alternative example of the second detection member; FIG. Illustratively illustrates components of a broadband illumination system in an embodiment of the metrology apparatus of FIG. 3; FIG. 7 illustrates components that house the apparatus of FIG. 3 and are partially formed at different vacuums or near vacuum and/or low Principles in the Environment; FIG. 8 illustrates the geometry of incident and reflected rays relative to a grating target in a metrology method in accordance with an embodiment of the present invention, wherein a non-zero azimuth is used; FIG. 9 schematically illustrates the execution of FIG. FIG. 10 is a flow chart illustrating a method for measuring weights according to an embodiment of the present invention; and FIG. 11 is a diagram illustrating a method for controlling weights and measures using measurements performed by the method and apparatus of FIGS. 1 through 10. And/or a flow chart of the method of lithography manufacturing process performance.

Before describing the embodiments of the present invention in detail, it is intended to present an example environment in which embodiments of the invention may be practiced.

Figure 1 shows the lithography apparatus LA as part of an industrial facility implementing a high volume lithography manufacturing process at 200. In this example, the fabrication process is adapted for use in the fabrication of semiconductor products (integrated circuits) on substrates such as semiconductor wafers. Those skilled in the art will appreciate that a wide variety of products can be manufactured by processing different types of substrates with variations of this procedure. The production of semiconductor products is purely used as an example of today's commercial significance.

Within the lithography apparatus (or in short, "litho tool 200"), the metrology station MEA is shown at 202 and the exposure station EXP is shown at 204. The control unit LACU is shown at 206. In this example Each substrate accesses the measurement station and the exposure station to be applied with a pattern. For example, in an optical lithography apparatus, the projection system is used to transfer a product pattern from a patterned device MA using an adjusted radiation and projection system. To the substrate, the transfer is performed by forming a pattern image in the layer of radiation-sensitive resist material.

The term "projection system" as used herein shall be interpreted broadly to encompass any type of projection system suitable for the exposure radiation used or for other factors such as the use of a immersion liquid or the use of a vacuum, including refraction, Reflective, catadioptric, magnetic, electromagnetic, and electrostatic optical systems, or any combination thereof. The patterned device MA can be a reticle or pleated reticle that imparts a pattern to a radiation beam that is transmitted or reflected by the patterned device. Well-known operating modes include step mode and scan mode. As is known, projection systems can cooperate with supports and positioning systems for substrates and patterned devices in a variety of ways to apply desired patterns across a plurality of target portions of the substrate. Instead of a reticle with a fixed pattern, a programmable patterning device can be used. The radiation may, for example, include electromagnetic radiation in deep ultraviolet (DUV) or extreme ultraviolet (EUV) bands. The invention is also applicable to His type of lithography program, for example, embossing lithography and direct lithography, for example, by electron beam.

The lithography apparatus control unit LACU controls all movements and measurements of various actuators and sensors to accommodate the substrate W and the reticle MA and perform a patterning operation. The LACU also includes signal processing and data processing capabilities to perform the calculations associated with the operation of the device. In practice, the control unit LACU will be implemented as a system of many sub-units, each sub-unit handling real-time data acquisition, processing and control of one of the subsystems or components within the device.

Prior to applying the pattern to the substrate at the exposure station EXP, the substrate is processed at the metrology station MEA so that various preliminary steps can be performed. The preliminary steps can include using a level sensor to map the surface height of the substrate and an alignment sensor to measure the position of the alignment marks on the substrate. The alignment marks are nominally configured in a regular grid pattern. However, the mark deviates from the ideal grid due to the inaccuracy of the mark and also due to the deformation of the substrate through its processing. Therefore, in addition to measuring the position and orientation of the substrate, the alignment sensor must also measure the position of many marks across the substrate area in detail (the product features at the correct position where the device will print with extremely high accuracy) in the case of). The device may be of the so-called dual stage type with two substrate stages, each substrate stage having a positioning system controlled by the control unit LACU. When one substrate on one substrate stage is exposed at the exposure station EXP, another substrate can be loaded onto another substrate stage at the measurement station MEA, so that various preliminary steps can be performed. Therefore, the measurement of the alignment marks is extremely time consuming, and providing two substrate stages results in a considerable increase in the yield of the device. If the position sensor IF is unable to measure the position of the substrate table while the substrate stage is at the measurement station and at the exposure station, a second position sensor can be provided to enable tracking of the substrate table at both stations position. The lithography apparatus LA can, for example, belong to the so-called dual stage type, which has two substrate stages WTa and WTb and two station-exposure stations and measuring stations - between which the substrate table can be exchanged.

In the production facility, the device 200 forms a "micro-shadow manufacturing unit" or a "micro-shadow cluster" The "lithographic fabrication unit" or "micro-shadow cluster" also includes a coating device 208 for applying a photosensitive resist and other coatings to the substrate W for patterning by the device 200. At the output side of the device 200, a bake device 210 and a developing device 212 are provided for developing the exposed pattern into a solid resist pattern. Between all such devices, the substrate handling system is responsible for supporting the substrate and transferring the substrate from one piece to the next. These devices, which are often collectively referred to as "coating and developing systems", are under the control of the coating and developing system control unit. The coating and developing system control unit itself is controlled by the supervisory control system SCS, and the supervisory control system SCS is also via lithography. The device control unit LACU controls the lithography device. Thus, different devices can be operated to maximize yield and processing efficiency. The supervisory control system SCS receives the recipe information R, which provides a detailed definition of the steps to be performed to produce each patterned substrate.

Once the pattern has been applied and developed in the lithography fabrication unit, the patterned substrate 220 is transferred to other processing devices such as those illustrated at 222, 224, 226. A wide range of processing steps are performed by various devices in a typical manufacturing facility. For the sake of example, device 222 in this embodiment is an etching station and device 224 performs a post-etch annealing step. Additional physical and/or chemical processing steps are applied to the additional device 226 and the like. Numerous types of operations may be required to fabricate actual devices, such as material deposition, surface material property modification (oxidation, doping, ion implantation, etc.), chemical mechanical polishing (CMP), and the like. In practice, device 226 can represent a series of different processing steps performed in one or more devices.

It is well known that the fabrication of semiconductor devices involves many iterations of this process to build device structures with appropriate materials and patterns layer by layer on the substrate. Thus, the substrate 230 that reaches the lithography cluster can be a newly prepared substrate, or it can be a substrate that has been previously processed in this cluster or completely in another device. Similarly, depending on the desired processing, the substrate 232 on the exit device 226 can be returned for subsequent patterning operations in the same lithography cluster, which can be designated for use. Patterning operations in different clusters, or they may be finished products to be sent for dicing and packaging.

Each layer of the product structure requires a different set of program steps, and the means 226 for each layer can be completely different in type. Additionally, even where the processing steps to be applied by device 226 are nominally the same, there may be several machines in parallel that operate in parallel to perform steps 226 on different substrates. Small differences or defects in the settings between such machines may mean that they affect different substrates in different ways. Even though the steps are relatively common for each layer, such as etching (device 222) may be performed by several etching devices that are nominally identical but operate in parallel to maximize yield. Moreover, in practice, the different layers require different etching procedures depending on the details of the material to be etched, for example, chemical etching, plasma etching, and require special requirements such as anisotropic etching.

Previous and/or subsequent procedures may be performed in other lithography apparatus as just mentioned, and previous and/or subsequent procedures may be performed even in different types of lithography apparatus. For example, some of the layers in the device fabrication process that are extremely demanding on parameters such as resolution and overlays can be performed in more advanced lithography tools than other layers that are less demanding. Therefore, some layers can be exposed to the infiltrated lithography tool while the other layers are exposed to the "dry" tool. Some layers can be exposed to tools that operate at DUV wavelengths, while others are exposed using EUV wavelength radiation.

In order to properly and consistently expose the substrate exposed by the lithography apparatus, it is necessary to detect the exposed substrate to measure properties such as overlay error, line thickness, critical dimension (CD), and the like between subsequent layers. Accordingly, the manufacturing facility positioned with the lithography fabrication unit LC also includes a metrology system 240 that houses some or all of the substrates W that have been processed in the lithographic fabrication unit. The metrology results are provided directly or indirectly to the supervisory control system SCS. If an error is detected, the exposure of the subsequent substrate can be adjusted, especially if the weights can be measured quickly and quickly enough to allow other substrates of the same batch to remain exposed. Moreover, the exposed substrate can be peeled off and Rework is done to improve yield or be discarded, thereby avoiding further processing of known defective substrates. In the case where only some of the target portions of the substrate are defective, additional exposure may be performed only for good target portions.

Where metrology system 240 is used, it can be determined, for example, that important performance parameters such as stacking or critical dimension (CD) do not meet the specified accuracy requirements in the developed resist. Prior to the etching step, there is an opportunity to strip the developed resist via the lithography cluster and reprocess the substrate 220. It is also known that by making small adjustments over time by the supervisory control system SCS and/or the control unit LACU 206, the metrology results 242 from the device 240 can be used to maintain the accurate performance of the patterning operation of the lithography cluster, thereby minimizing The risk of producing unqualified products and requiring heavy work. Of course, the hybrid metrology system 240 and/or other metrology devices (not shown) may be utilized to measure the properties of the processed substrates 232, 234 and the incoming substrate 230.

Each generation of lithography manufacturing technology (often referred to as a "node" of technology) has a more stringent specification of performance parameters such as CD. One of the major challenges in metrology is that the metrology target size also requires less than the target typically used with the metrology device 240. For example, the current goal should be to use targets having a size of 5 microns x 5 microns or less. These small sizes will allow for the wider use of so-called "in-grain" or "on-product" metrology, where the target is located in the product features (instead of being confined to the area of the kerf between product areas).

Within the metrology system 240, a first metrology device 242 (MET1) and a second metrology device 244 (MET2) are provided and additional devices (MET3, etc.) are provided as appropriate for the product at the desired stage in the manufacturing process The parameters are measured. A common example of a metrology device in a modern lithography production facility is a scatterometer, such as an angular resolution scatterometer or a spectral scatterometer, and which can be applied to measure the developed substrate at 220 prior to etching in device 222. Attributes. By providing a plurality of metrology devices 242, 244, etc., multiple types of measurements can be performed to obtain a pair A preferred total measurement of one or several of the parameters of interest is given for a given target structure, or of course separation measurements of different parameters of interest are obtained. The metrology devices 242, 244, etc. can be provided as separate units for loading and unloading substrates and alternatively for each type of measurement unloading substrate, two or more of which can be integrated into a hybrid metrology The device is such that it can act on a common substrate. An example of such a hybrid metrology apparatus is disclosed in European Patent Application No. 15202273.7, which is incorporated herein by reference in its entirety.

Each of the metrology devices 242, 244 can have a particular illumination system for radiation having particular characteristics. A more detailed example of the types of devices that can be combined is given below. In each case, the metrology processing system 246 receives the first spectral data 248 from the first detection system within the first metrology device 242 and the second spectral data 250 from the second detection system within the second metrology device 244. The metrology processing system 246 combines the spectra in a hybrid calculation to obtain a measurement 252 of the CD or other parameters reported to the supervisory control system SCS. In some embodiments, the metrology processing system 246 also controls the operation of one or more of the metrology devices 242, 244 to vary the parameters of its operation based on spectral data received from the other of the metrology devices.

One of the metrology devices, such as the second metrology device 244, can be designed to operate with radiation at visible or UV wavelengths, while the other of the devices, such as the first metrology device 242, can be designed to utilize EUV radiation. operating. In other embodiments, both the first and second metrology devices can be designed to operate with EUV radiation having the same or different wavelengths. One of the devices can be designed to operate with a grazing incidence while the other is designed to operate with a normal incidence or near normal incidence. One of the devices can be designed to obtain a frequency resolved spectrum of the radiation scattered by the target structure, while the other of the devices is designed to obtain an angular resolution spectrum. One of the metrology devices, such as the second metrology device 244, can be an angular resolution scatterometer, a spectral scatterometer, a spectroscopic ellipsometer, and/or a spectral Mueller ellipsometer. These and other variants can be used for mixing The system obtains more information about the structure and thus gives a more accurate measure of the parameter of interest. Three or more than three metrology devices can be disposed within the metrology system 240, and the first and second metrology devices are labeled herein for convenience only. These additional metrology devices can all be used together to make a measurement, or they can be used in different sub-combinations. In the example of the hybrid metrology system mentioned above, some common hardware may be used to implement more than one of these types of metrology devices.

In an embodiment of the hybrid metrology system 240 in accordance with the present invention, it is proposed to use EUV wavelengths for metrology in at least one of the metrology devices. In some embodiments, EUV reflectometry (particularly for spectral EUV reflectometry) is used as part of the CD metrology solution for future technology nodes. In the above-referenced International Patent Application No. PCT/EP2016/056254, the exemplary EUV reflectometry provides a high sensitivity benefit that is robust to program changes and selective for the parameter of interest. of.

Similar to optical scatterometers used in today's production facilities, EUV metrology devices can be used to measure structures within resist materials processed in lithographic fabrication units (referred to as "post-development detection" or ADI), and / Or to measure the structure after it has been formed of a harder material (referred to as "post-etch detection" or AEI). For example, the EUV metrology device 242 can be used to detect the substrates after they have been processed by the developing device 212, the etching device 222, the annealing device 224, and/or other devices 226. In contrast, X-ray technology will generally be limited to AEI and cannot be used to measure structures that are only formed in the resist. This situation limits the possibility of reworking the substrate in the event that the substrate is rejected.

EUV spectral reflectometry

FIG. 2 illustrates an EUV metrology method, while FIG. 3 illustrates an EUV metrology apparatus 300. The apparatus can be used as a first metric for measuring the parameters of the substrate W processed in the production facility of FIG. An example of setting 242 or second metrology device 244.

In Fig. 2, the target T is schematically represented as a one-dimensional grating structure at the origin including the spherical reference coordinate system. The axes X, Y, and Z are defined relative to the target. (Of course, any arbitrary coordinate system can be defined in principle, and each component can have its own local reference coordinate system that can be defined relative to the displayed reference coordinate system). The periodic direction D of the target structure is aligned with the X axis. This one-dimensional grating structure takes the shape of a series of periodic lines in the grating, but is only one example of many possible target structures. Other examples include features in a 2-D array, similar to contact holes or pillars in device patterns. In other cases, the target structure can be a multi-layer structure that has no change in X or Y.

This illustration is not a true perspective view but is merely illustrative. The X-Y plane is the plane of the target and the substrate, and is shown tilted toward the viewer for clarity, which is represented by an oblique view of the circle 302. The Z direction defines a direction N perpendicular to the substrate. In Figure 2, one of the incident rays is labeled 304 and has a grazing incidence angle a. In this example, incident ray 304 (and all incident rays that form radiation spot S) are substantially in a plane parallel to the X-Z plane, which is a plane defined by directions D and N and represented by circle 306. The reflected ray 308, which is not scattered by the periodic structure of the target T, is emitted in the illustration toward the right side of the target at an elevation angle a.

To perform spectral reflectometry, the ray 308 and other reflected rays are resolved into a spectrum 310 comprising rays of different wavelengths. For example, grazing incidence diffraction grating 312 can be used to generate the spectrum. The spectrum 310 includes one or more higher order radiations that are diffracted by the grating 312 and detected by the detector 313. The detector, which may be, for example, a CCD image detector with a pixel array, is used to transform the spectrum into electrical signals and ultimately into digital data for analysis.

In a practical system, the spectrum of illumination radiation (i.e., radiation including incident ray 304) can undergo time variations that would interfere with subsequent analysis. In order to normalize the detection of such changes To the spectrum, a reference spectrum is captured by the second detector 314. To generate a reference spectrum, source radiation 316 is diffracted by another diffraction grating 318. The zero-order reflected rays of the grating 318 form the incident ray 304, and the one-step diffracted ray 320 of the grating 318 forms the reference spectrum detected by the reference spectral detector 314. Electrical signals and data representing the reference spectrum are obtained for analysis.

The measurement of the properties of the target structure T can be calculated from the measured spectra obtained for one or more values of the angle of incidence a. In the metrology system 240, this measurement can be obtained by using the detected spectrum in combination with one or more spectra detected by other metrology devices on the same target structure. Different ways of making this combination are further described in the above-referenced European Patent Application No. 15202273.7.

Turning to FIG. 3, an EUV metrology apparatus 300 is provided for measuring the properties of the metrology target T formed on the substrate W by the method of FIG. Various hardware components are schematically represented. The practical implementation of such components can be performed by a skilled artisan applying a mixture of existing components and specially designed components in accordance with well-known design principles. Supports (not shown in detail) are provided for holding the substrate in a desired position and orientation relative to other components to be described. Radiation source 330 provides radiation to illumination system 332. Illumination system 332 provides an EUV radiation beam, represented by ray 304, which forms a focused irradiance spot on target T. Lighting system 332 also provides reference spectrum 320 to detector 314. Components 312, 313, etc. are conveniently considered to be detection system 333.

The substrate W in this example is mounted on a movable support having a positioning system 334 such that the angle of incidence a of the ray 304 can be adjusted. In this example, the substrate W is selected to tilt the incident angle as conveniently, while the source 330 and illumination system 332 remain stationary. To capture the reflected ray 308, the detection system 333 is provided with an additional movable support 336 such that the movable support moves at an angle 2α relative to the stationary illumination system or at an angle a relative to the substrate. In the grazing incidence system of EUV reflectometry, it is convenient to define the angle of incidence α by reference to the plane of the substrate, such as Shown. Of course, the angle of incidence can likewise be defined as the angle between the direction of incidence of the incident ray I and the direction N perpendicular to the substrate.

Additional actuators (not shown) are provided to bring each target T into position where the focused radiation spot S is positioned. (On the other hand, bring the spot to the position where the target is located). In practical applications, there may be a series of individual targets or target sites to be measured on a single substrate, and a series of individual targets or target sites to be measured may also exist on a series of substrates. In principle, it is not important whether the substrate and the target move and reorient when the illumination system and the detector remain stationary, or whether the substrate remains stationary when the illumination system and the detector move, or by such techniques. Whether the combination achieves a different component with relative movement. The present invention covers all such variations.

As has been described with reference to Figure 2, the radiation reflected by target T and substrate W is split by grating 312 into a spectrum 310 of rays having different wavelengths before it is illuminated onto detector 313. The detector 313 includes, for example, a position sensitive EUV detector, which is typically an array of detector elements. The array can be a linear array, but in practice a 2-dimensional array of components (pixels) can be provided. The detector 313 can be, for example, a charge coupled device (CCD) image sensor.

The processor 340, which may be part of the metrology processing system 246 or the subsystem of the metrology device 300, receives signals from the detectors 313 and 314. In detail, the signal ST from the detector 313 represents the target spectrum, and the signal SR from the detector 314 represents the reference spectrum. Processor 340 can subtract the reference spectrum from the target spectrum to contain a reflection spectrum of the target that is normalized with respect to changes in the source spectrum. The resulting reflectance spectra for one or more angles of incidence are used in processor 340 to indirectly calculate measurements of target properties such as CDs or overlays.

In practice, the radiation from source 330 can be provided by a series of short pulses, and signals SR and ST can be captured together for each pulse. Each individual pulse is aggregated at this angle of incidence for this purpose Before the target total reflection spectrum, the difference signal for each individual pulse is calculated. In this way, the instability of the source spectrum between the pulses is corrected. The pulse rate can be thousands or even tens of thousands (Hz) per second. The number of pulses that are aggregated to measure a reflectance spectrum can be, for example, tens, hundreds, or thousands. Even with so many pulses, physical measurements take only a fraction of a second.

First and second detection systems

Raster 312 and detector 313 can be considered together as the first detection system 333 in the apparatus of FIG. The first detection system 333 can further include a grating 318 and a detector 314 that generate a reference spectral signal SR. EUV radiation included in spectrum 310 can be considered as radiation in the first band. The radiation that forms the spectrum 310 on the detector 313 is not diffracted to form a zero-order radiation beam 350, as illustrated in Figures 2 and 3. Where the illumination radiation from source 330 and illumination system 332 includes a wavelength range that is much longer than the EUV radiation diffracted by grating 312, such radiation will actually be included in zero order radiation 350. This is because the grating pitch of the grating 312 is tuned to a much shorter wavelength in the first band and is too short to be "seen" by the longer wavelength of the second band. In accordance with the principles of the present invention, the second detection system 352 and/or the additional detection system is configured to receive the zero-order radiation and perform further analysis in the second and/or additional bands.

The second detection system 352 provides one or more additional signals SA, as will be described in more detail later. In instances where source 330 and illumination system 332 can simultaneously deliver broadband radiation including radiation in the first and second bands, additional signals SA can be obtained simultaneously with obtaining signals ST and SR without necessarily incurring any additional exposure. Time or adjustment. The radiation 350 reflected by the first spectral grating 312 also provides a convenient source of information, even in the case of sequentially and not simultaneously generating radiation in the first and second bands, thereby avoiding additional optical systems near the target T. Need.

Additional signals SA from the second and/or additional detection system 352 may be used by the processor 340 to The measurement accuracy of the measurement calculated from the EUV spectral signal ST is enhanced. In the case of using only a single band of radiation, the accuracy achieved is limited by the cross-correlation between the optical properties of the material and the geometric properties of the target structure (multilayer and/or grating). By increasing the diversity in the data (especially in terms of wavelength), the accuracy of measurements such as CD and overlay parameters can be improved. Alternatively or additionally, as shown by the dashed lines, the additional signal SA is used by or in the processor 340 for the purpose of complete separation measurements.

In the illustrated example, the first waveband includes EUV radiation and the first detection system is an EUV spectral reflectometer (including spectral grating 312). In this application of EUV-SR to metrology in semiconductor manufacturing, small grating targets can be used. For example, such grating targets can have dimensions less than 10 microns in each direction X and Y. The detectors 313 and 314 are used to capture a plurality of diffraction spectra while setting the grazing incidence angle α to various values. Where the detected spectra and mathematical models of the target structure are used, the reconstructive calculations can be performed to obtain measurements of the CD and/or other parameters of interest. An example reconfiguration method is illustrated in Figure 10, described below. In a metrology system that is the subject of the present invention, the reconstruction method can be modified to take into account spectral or other analytical information detected by two or more detection systems operating in different bands, not only by The spectrum in the first band represented by signal ST.

In the case of a brief consideration of the target itself, the size of the line and space will depend on the target design, but the period of the structure can be, for example, less than 100 nm, less than 50 nm, less than 20 nm, or even less than 10 nm and down to 5 Nano. The lines of the grating structure can have the same dimensions and spacing as the product features in the product area of the substrate. For the purposes of weights and measures only, the line of the grating structure may in fact be the line of the product structure, rather than the line of the target structure formed within the dedicated target area. Such small features can be formed, for example, by embossing lithography or by direct writing in an EUV lithography program. Modern DUV lithography can also be formed by a so-called double patterning process (usually multi-patterning) These small features. Techniques in this category include, for example, doubling the distance between lithography-etch-lithography-etch (LELE) and self-aligned dual damascene in a back end-of the line (BEOL) layer. For purposes of explanation, the CD will be assumed to be the parameter of interest in the following examples. However, in the case where there are two gratings formed on top of each other, another parameter of interest may be a superposition. This stack pair can be measured based on the asymmetry in the EUV-SR diffraction order. Any unintentional positional offset between different groups of features in the multi-patterning process can be considered in the form of a stack and can be performed by techniques similar to those used to measure the overlay between layers. Measure. Additionally, overlapping pairs of features in the underlying layer or overlying layer may be different for each population when multiple populations of features are formed in a single layer, and each of such groups may be separately measured as needed Stacked pairs. The technique for measuring pairs of these types is further described in the above-referenced European Patent Application No. 15202273.7. The angle of incidence can be increased as necessary to achieve proper penetration of EUV radiation into the substructure.

4 illustrates an example of a second detection system 352 that can be configured to receive zero-order reflected radiation 350 in the apparatus of FIG. 3 in more detail. In this example, the additional signal SA represents the spectrum of the radiation reflected by the target T in the second band, which is assumed to contain a spectrum 310 having a wavelength longer than the EUV radiation, which spectrum 310 is detected by the detector 313. The second detection system 352 has a form very similar to the first detection system, and includes a second spectral grating 354 and a second detector 356. The second spectral grating 354 diffracts a portion of the radiation in the second wavelength band to form a second spectrum 358 that is detected by the second detector 356. An additional signal indicates this second spectrum.

The second detection system 352 can include additional components, such as a wavelength selective filter 360 and an analyzer 362 for selecting radiation of a particular polarization, but such components are purely optional.

In the case where the second detection system 352 includes the spectral grating 354, the grating outputs zero-order reflected radiation 370 in addition to the second spectrum 358. And can be used in the second detection system The zero order radiation 350 from the first spectral grating 312 is in the same manner so that the zero order radiation 370 from the second spectral grating 354 can be delivered to the third detection system 372. Additionally additional signal SA2 may be generated by the third detection system and used alone or in combination with additional signals that have been received by processor 340 to improve measurement accuracy and/or allow for different measurements. Additionally, within the third detection system 372, there may be a spectral grating that delivers zero-order reflected radiation 380 to the fourth detection system 382, and the like. Further additional signal SA3 may be generated by the fourth detection system and used alone or in combination with additional signals that have been received by processor 340 to improve measurement accuracy and/or to allow for different measurements.

The choice of different bands is based on design choices and practicality. Purely by way of example, in the examples of the present invention, it is assumed that the first wave band contains EUV radiation, for example including wavelengths in some or all of the range of 1 nm to 100 nm. Each additional band (such as a second band, a third band, etc.) may be, for example, longer than the first band. For example, the second band may comprise a longer wavelength portion of the EUV band, or it may comprise a wavelength longer than 100 nm. For example, the second waveband can comprise wavelengths in the range of from 100 nanometers to 300 nanometers, including so-called vacuum UV and/or deep UV radiation. Alternatively, the second waveband may comprise wavelengths longer than 300 nanometers, such as radiation in the UV and/or visible and/or infrared wavelengths. Similarly, in the case of analyzing the radiation in the third band, the wavelength in the third band may be longer than the wavelength in the second band and may include, for example, ultraviolet, visible, and/or infrared wavelengths.

In principle, the sequence of bands throughout the first, second, and third detection systems does not need to be wavelength-increasing, but in a practical system, this is likely to be the most convenient configuration. One reason for this is that in the case where the detection system includes a spectral diffraction grating, the grating lines formed to diffract the radiation in one of the bands will generally be invisible to the radiation and the longer band, making it possible to spectrally Their longer wavelength bands are found in the zero-order reflected radiation. In addition, there are several bands that traverse Radiation sources of broadband radiation often produce a greater number of photons in longer wavelengths than in shorter wavelengths. As a result, photons in short wavelength bands such as EUV bands tend to be more "rare" than longer wavelengths such as ultraviolet, visible, and infrared. Since some portion of such photons will be lost at each optical component, it is desirable to process less redundant photons of, for example, EUV and/or VUV photons as close as possible to the target in the total optical path. We can allow more redundant longer wavelength photons to have some loss before they are detected in the downstream portion of the total optical system. Additionally, optical systems that process photons at the shortest wavelengths (such as EUV and VUV) may need to be housed in a particular environment, such as a low pressure (near vacuum) atmosphere. By locating the detection system for such shorter wavelengths upstream of the detection system for longer wavelengths, the detection system for longer wavelengths can be housed outside of the special environment, thereby substantially reducing the device Cost and size.

In the example of FIG. 4, it is assumed that each of the second, third, and fourth detection systems includes a spectral detection system of spectral gratings and detectors. If necessary, reference signals in one or more of the other bands may be included in the reference signal SR or the additional reference signal. In some cases, the source can be well characterized such that by measuring the fluctuations of the first (EUV) band, the processor 340 can derive a reference spectrum for the other band. However, if necessary, add additional rasters and detectors (not shown) upstream of the target structure. Care can be taken that this grating does not induce undue loss of EUV radiation.

However, spectroscopy is only one example of the type of analysis that can be performed in each band. The invention is not limited to the use of spectroscopy as the only form of analysis in each detection system.

FIG. 5 illustrates an alternative form of, for example, a second detection system 352 that is designed for ellipsometry. Polarization analyzer 500 receives zero order radiation 350 from spectral pattern grating 312 of the first detection system and filters out the predetermined polarization of the radiation. Wavelength selective filters 504 and/or other filter elements may also be provided. The filtered radiation is detected by the detector 502 to An additional signal SA is generated for use by the processor 340. As previously mentioned, the additional signal SA can be used in conjunction with the signals SR and ST from the first detection system to enhance the accuracy of the calculated measurements of CDs, overlays and other parameters. Alternatively or additionally, additional measurement attempts can be used for separate calculations. A single value of the intensity of the radiation from detector 502 is not likely to yield much information. However, in combination with the change in the angle of incidence α, more information is available.

Figure 6 illustrates a particular form of radiation source 330 that may be used in the apparatus of Figures 3 through 5. Any type of radiation source can be used with the proviso that it provides the appropriate quality of the radiation in the desired band. In principle, the radiation in the first wave band, the second wave band or the like may be sequentially provided, but in the case where the radiation in the different wave bands is simultaneously present in the illumination radiation, the maximum yield of the device may be obtained from This radiation is obtained by a different individual source, or may be obtained from a single broadband source of the type illustrated in FIG. Types of radiation sources that may be considered include an inverse Compton source (ICS), a small synchrotron source, a laser generated plasma source (LPP), a discharge generated plasma source (DPP), and a high order harmonic generator source (HHG). .

The radiation source 330 in the example of FIG. 6 is an HHG source for generating EUV radiation based on high order harmonic generation (HHG) technology. Such sources are commercially available, for example, from KMLabs (http://www.kmlabs.com/), Boulder Colorado, USA. The main components of the radiation source are pump laser 630 and HHG gas cell 632. Gas supply 634 supplies a suitable gas to the air cells where it is ionized by power source 636 as appropriate. The pump laser can be, for example, a fiber-based laser with an optical amplifier to produce pulses of infrared radiation that last less than 1 ns (1 nanosecond) per pulse, with pulse repetition rates as large as several megahertz as needed. The wavelength can be, for example, about 1 [mu]m (1 micron). The laser pulse is delivered as a first radiation beam 640 to the HHG gas cell 632 where a portion of the radiation is converted to a higher frequency. Beam 642 is emitted from HHG gas cell 632, which includes coherent radiation having a desired wavelength.

Radiation can contain multiple wavelengths. If the radiation is also monochromatic, the measurement calculation (reconstruction) can be simplified, but in the case of HHG, it is easier to generate radiation having several wavelengths. These situations are design choice issues and can even be a selectable option within the same device. Different wavelengths will provide different levels of contrast, for example, when imaging structures of different materials. For example, to detect a metal structure or germanium structure, different wavelengths can be selected for use in imaging (carbon based) resist features or for detecting wavelengths of contamination of such different materials. One or more filter devices (not shown) may be provided. For example, a filter such as an aluminum (Al) film can be used to cut the fundamental IR radiation from further transfer into the detection device. A grating may be provided to select one or more specific harmonic wavelengths from among the wavelengths produced in the gas cell. Some or all of the beam paths may be included in a vacuum environment, keeping in mind that EUV radiation is absorbed as it travels through the air. The various components of radiation source 330 and illumination optics 332 can be adjustable to implement different metrology "formulations" within the same device. For example, different wavelengths and/or polarizations can be made selectable.

For high volume manufacturing applications, the choice of the appropriate source will be guided by cost and hardware size, not just by theoretical capabilities, and the HHG source is chosen here as an example. Other types of sources that are applicable in principle are also available or under development. Examples are synchrotron sources, free electron laser (FEL) sources, and so-called x-ray lasers. Sources based on inverse Compton scattering can also be used. Plasma-based sources such as DPP sources and LPP sources also provide radiation in multiple wavelength bands, including EUV. Plasma sources for generating EUV radiation include sources based on, for example, tin (Sn), and include sources based on Xe or Ar or Kr or Ne or N, or any combination thereof.

The filtered beam 642 enters the detection chamber from the first radiation source 330, and in the detection chamber, the substrate W including the structure of interest is held by the substrate support 616 for detection. The structure of interest is labeled T. The atmosphere within the detection chamber 1050 is maintained by the vacuum pump 1052 to near vacuum so that EUV radiation can pass through the atmosphere without undue attenuation. Lighting system 332 includes The radiation is focused into an element 654 of the focused beam 656 and may comprise, for example, a two-dimensional curved mirror or a series of one-dimensional curved mirrors as described in the prior application mentioned above. Diffractive gratings such as spectral gratings 312 and 318 can be combined with such mirrors as desired. Focusing is performed to achieve a circular or elliptical spot having a diameter of less than 10 microns when projected onto the structure of interest. The substrate support 616 includes, for example, an X-Y translation stage and a rotating stage. By X-Y translating the stage and rotating the stage, any portion of the substrate W can be brought to the focus of the beam in the desired orientation. Therefore, the radiation spot S is formed on the structure of interest.

The outline of the second metrology device labeled MET2 is also shown in FIG. This profile illustrates where the illustrated layout allows for the space of the second and second detection systems for the same target structure to be utilized within the metrology device 240.

Experimental results and simulations are presented to illustrate the choice of wavelengths that can be used in the device and the choice of angle of incidence that can be used in the device, in International Patent Application No. PCT/EP2016/056254, the disclosure of which is incorporated herein by reference. Particularly in the wavelength range of 15 nm to 40 nm and over 40 nm, it is seen that the reflection of several materials of interest remains substantially as high as 10, 20 and 30 degrees. Referring again to Figures 4 and 5, this range of angles of incidence allows for the implementation of an optical design that achieves a desired small spot of radiation, even under grazing incidence using available EUV optics. The international patent application in this application further explains how the illumination can be incident with respect to the periodic direction of the target T not only in the polar direction but also in the azimuthal direction in the case of a "conical mounting" configuration. Angles for improved accuracy.

FIG. 7 schematically illustrates different portions of a metrology device 900 that can accommodate the devices of FIGS. 3 and 4. This containment configuration features features that are particularly useful in facilitating the management of vacuum and low pressure atmospheres within the device in a high volume manufacturing environment. As already explained with reference to Figure 16, the EUV radiation signal will be severely attenuated unless the beam path is included in a vacuum or low pressure environment. At the same time, if you stay in a large capacity Using the device in a manufacturing environment, the operations schematically represented at 902 will be performed frequently to exchange the substrate W currently in the device with the new substrate W'.

In the example metrology apparatus 900, different components of the EUV optical system are contained in different chambers 904, 906, 908. Suitable walls define such chambers, while windows 910 and 912 permit EUV radiation to pass between the chambers. Each window 910, 912 can comprise a solid diaphragm or can comprise a simple aperture that is differentially twitched to maintain a desired atmospheric condition on either side of the window. The first chamber 904 contains a source 330 and an illumination system 332. A first atmospheric condition, such as a high vacuum, is maintained in chamber 904 by a suitable pumping and control system (not shown). The first window 910 permits the incident beam 304 to enter the second chamber 906 where the target is supported on the substrate W. In the second chamber 906, a second atmospheric condition around the target is maintained. For example, the second atmospheric condition can be a low pressure gaseous atmosphere. In this manner, when the substrates W and W' are exchanged by some form of air lock mechanism, the desired atmospheric conditions can be established and re-established relatively quickly, without undue cost. Although the transmission loss in the second atmospheric condition can be an order of magnitude greater than in high vacuum, such losses can be tolerated for limited travel distances and operational productivity.

In this example, components of first detection system 333, such as grating 312 and detector 313, are located in third chamber 908, which is maintained in a third atmospheric condition. For example, the third atmospheric condition can be a high vacuum. The second window 912 permits the reflected ray 308 to enter a detection system in the chamber 908 that carries spectral information about the target on the substrate.

It may be noted that if windows 910 and 912 have a limited range, the geometry of device 900 in this example greatly defines the range of incident angles a that may be used. A variant of the device of Figure 7 is illustrated in the International Patent Application No. PCT/EP2016/056254, the entire disclosure of which is incorporated herein by reference. Other approaches may also be considered, for example, by providing a plurality of discrete windows suitable for different angles of incidence, and/or by accommodating at least some components of the detection system in the same chamber as the sample Within 906 it is allowed to move without losing its view through a window.

The cost and implication of the space within the controlled atmosphere environment is provided to the owner of the metrology device and the builder and operator. Therefore, for each of the second detection system 352, the third detection system 372, and the fourth detection system 382, it can be determined whether the detection system should be located in a low pressure environment or at a standard atmospheric pressure (less expensive) ) Environment or the like. In the example illustrated in FIG. 7, second detection system 352, which may be configured, for example, to obtain a spectrum of radiation in a vacuum UV band, is located inside a controlled environment of chamber 908. In contrast, the third detection system 372 and the fourth detection system 382 are located outside of the chamber 908. Thus, for example, the detection system can be configured to obtain a spectrum of radiation in the vicinity of the UV band, and the fourth detection system 382 is configured to obtain a spectrum of the radiation in the visible band. In an alternative example in which, for example, only a second detection system is present for analyzing radiation in the UV and/or visible light bands, the second detection system 352 can be external to the chamber 908.

FIG. 8 illustrates a modified metrology method, and FIG. 9 illustrates a corresponding metrology device 1300. Unless otherwise mentioned, components labeled "13xx" in these examples shall be considered identical to the components labeled "3xx" in the device of Figure 3. Thus, for example, the modified device includes a lighting system 1330, an illumination system 1332, a first detection system 1333, and a second detection system 1352. However, compared to the apparatus of Figure 2, the positioning system 1334 is operable such that the angle of incidence of the incident ray 1304 can vary not only in terms of the grazing incidence angle a, but also in the azimuth angle labeled φ herein.

Again, the X, Y, Z coordinate system is defined relative to the substrate. Again, assume that the target T contains a one-dimensional grating having a periodic direction D parallel to the X-axis of the substrate. Again, the substrate and target can be tilted to vary the angle of incidence. However, a non-zero incident azimuth angle φ is allowed. The azimuth angle φ is defined with respect to the periodic direction D of the grating target T. (D can be either the main periodic direction in the case of a two-dimensional periodic target). That is, when the incident direction is projected onto the plane of the substrate, The azimuth angle φ between the ray and the periodic direction D is non-zero and can be extremely large. That is, the irradiation direction is outside the plane defined by the periodic direction D and the direction N perpendicular to the substrate. The reality is that the incident ray travels in a plane that is inclined with respect to the periodic direction D. The oblique plane is represented by a circle 1307 which is orthogonal to the plane of the substrate but oblique to the periodic direction and the X-Z plane. It should be understood that although the selection of the labels for the plane and the axis is arbitrary, the grazing incidence angle and azimuth are defined with reference to the physical properties of the periodic structure of the target. The inventors have recognized that the diffraction efficiency of different diffraction orders can be substantially increased when non-zero azimuth angles are used. This situation in turn has an effect on the spectrum of the reflected (zero order) ray 1308.

When the device 1300 is implemented, different configurations of the positioning system can be used to achieve a non-zero azimuth. Element symbol 1334 indicates a positioning subsystem having an actuator for rotation about the X and Y axes of the substrate. For the desired combination of the grazing incidence angle a and the azimuth angle φ, the appropriate command values Rx and Ry are calculated to cause the substrate to tilt in two dimensions to achieve the desired angle. In another implementation, an actuator may be provided for rotation and tilting to directly drive the angles a and φ. As can be appreciated from Figure 8, the rotation Rz corresponds directly to the desired azimuth angle φ, and in this case, the command value can be generated more directly from the desired measurement angle.

In other metrology regions, the type of installation required to vary both the grazing incidence (polar) angle and the azimuth is referred to as a "conical mounting table" and may also be used in this EUV reflectometry device. In general, those skilled in the art will appreciate that any form of command and any form of actuation mechanism can be used to implement this example with the proviso that it is suitable for achieving a known non-zero incident azimuth. It should also be understood that what is important is the relative orientation of the incident direction to the target (and (of course) the correct X-Y positioning of the target relative to the radiation spot S).

As mentioned above, the use of a non-zero azimuth allows for the use of the conical mounting of Figures 8 and 9 to enhance the diffraction efficiency compared to the configurations of Figures 2 and 3. This situation can provide a stronger signal to use Measure the specific attributes, thereby reducing the measurement time and/or increasing the measurement accuracy. Another benefit of using a non-zero azimuth can already be seen in Figure 8 by comparison with Figure 3. Note that the spot S (if it becomes elongated due to the angle of incidence of the tilt) is elongated in the direction defined by the azimuth. Therefore, the longest dimension of the spot is aligned with the diagonal direction of the target. In the case where most of the targets will be rectangular in shape, in fact this diagonal elongation of the spot allows the larger spot to be integrated into the target area as a whole. Thus, for a given illumination intensity, a larger total power of the radiation can be measured at the target, and thus the signal at the detector will increase proportionally. This effect alone allows for a slight shortening of the measurement time. Alternatively or additionally, the focus tolerance can be relaxed, which also shortens the measurement time.

More information on the use of conical mountings in EUV metrology is given in the aforementioned PCT application. All of the explanations and variations discussed above with reference to Figures 2 through 7 are applicable to the methods and apparatus of Figures 8 and 9. The method and apparatus of Figures 8 and 9 can be applied to any of the application examples mentioned below.

Applications

As mentioned previously, the additional signals SA, SA2, SA3, etc. obtained by the second, third detection system, etc., can be combined with the spectra obtained by the first detection system 333 in a variety of ways. A number of application examples are presented in the prior European patent application 15202273.7, and all such application examples will not be repeated here. Instead, we present a single instance here where the additional information is combined with the EUV spectrum in a reconstructed method type.

10 is a flow chart of a method of measuring parameters of a target structure using, for example, the metrology apparatus 240 described above. As described above, the target structure can be on a substrate such as a semiconductor wafer. This target structure will often take the shape of a series of periodic lines in the grating, or the shape of the structure in the 2-D array. The purpose of the metrology technique should be to measure one or more parameters of the shape by calculation from the observed interaction with the radiation. In the reconstruction technique disclosed herein, effectively The use of rigorous diffraction theory to calculate which values of these parameters will result in a particular observed diffraction spectrum. In other words, target shape information is obtained for parameters such as critical dimension (CD) and overlay. The stack-to-weight measure is a measurement technique that measures the stacking of two targets to determine if the two layers on the substrate are aligned. The CD (or critical dimension) is the width of the object "written" on the substrate and is the limit at which the lithographic apparatus can be physically written on the substrate. In some cases, the parameter of interest may be CD uniformity rather than the absolute measurement of the CD itself. Other parameters such as edge placement error (EPE), layer height (thickness), and sidewall angle (SWA) can also be measured as needed. In principle, any parameter of the shape that has an influence on the spectrum can be measured in this way. The parameters of interest may also include parameters related to the properties of the material within the structure, rather than parameters related to the shape of the structure.

The measurement of the shape and other parameters of the structure can be performed in a number of ways using the modeling of the resulting combined structure from the metrology device 240 and its diffraction properties. Referring to, for example, the example of FIG. 3 or FIG. 9, signals may be obtained from the first and second detection systems, etc., which represent spectra of radiation reflected by the target T in different bands. In the first type of program represented by Fig. 10, the spectrum based on the first estimate of the target shape (first candidate structure) is calculated and compared to the observed spectrum. The parameters of the model are then systematically varied and the diffraction is recalculated in a series of iterations to produce a new candidate structure and thus a best fit. In the second type of procedure, the spectra for many different candidate structures are calculated in advance to produce a "library" of spectra. Next, compare the spectra of the self-measured target observations with the calculated spectra to find the best fit. Two methods can be used together: a rough fit can be obtained from the library, followed by a repeat procedure to find the best fit.

The term "spectrum/spectra" in this context may refer to the frequency resolved spectrum in the spectral scatterometer of Figures 2 and 3. Spectra obtained by different detection systems in different bands can be treated as part of the larger spectrum observed or calculated, or they can be used individually for calculation In different parts of the program. Thus, for example, visible light band spectra and EUV band spectra can be used simultaneously to constrain all floating parameters of the model, or visible band spectra can be used first to constrain certain parameters, which are then processed while processing the EUV spectrum. Treated as fixed. In either case, additional information available from the second and third detection systems, etc., can improve the accuracy of the results.

The third type of procedure omits the modeled structure and its steps of interacting with the detected radiation, and applies machine learning to correlate the characteristics of the observed spectrum with the parameters of the structure. Machine learning can be based on a training set of spectra from actual structural observations that are coupled to direct measurements of the parameters of the structure that will be unknown parameters in future measurements. Machine learning may also be based on a training set of spectra obtained by modeling (simulating) interactions with mathematically modeled structures as used in the "Library" program described above. The training materials based on the simulation and the training data based on the actual observations can be combined into a larger training set as needed.

Returning to the first type of procedure, purely by way of example, the manner in which the target shape and/or material properties can be measured using an angle resolved scatterometer will be briefly described with reference to FIG. Perform the following steps. The steps will be listed here and then explained in more detail:

S11: accommodating the substrate with the target

S12: Define the measurement formula

S13: Measurement spectroscopy

S14: Defining the model formula

S15: Estimating shape parameters

S16: Calculating model spectra

S17: comparing the measured pattern with the calculated pattern

S18: Calculating the quality function

S19: Generate revised shape parameters

S20: Report final shape parameters

At S11, a substrate W having one or more metrology target structures T thereon is housed. For this description, it will be assumed that the target structure is periodic (1-D structure) in only one direction. In the case where the target is periodic (2-dimensional structure) or not completely periodic in both directions, the processing will be adapted accordingly. At S12, a measurement recipe is defined. The recipe defines any number of parameters to be used for illumination and detection settings in a particular application. The formulation may also specify one or more combinations of wavelengths and polarizations for incident radiation. This recipe defines a specific angular distribution for illumination and detection. This formulation specifies the intensity of the incident radiation and the exposure time. Also for example, the phase or coherence of the source can be part of a measurement recipe.

At S13, in the case of having a target structure positioned at spot S, the spectrum of the structure on the substrate is measured using the apparatus of the general type illustrated in Figures 2 and 3 or Figures 8 and 9. The measured spectra are captured by detectors 313, 356, etc. and passed to a computing system within processor 340. In order to obtain a robust measurement via reconfiguration, several sub-recipes can be used to capture several spectra of the same target. The spectra captured in this manner constitute observational data that can be used to determine the properties of the target structure, whether directly or indirectly.

It should be noted that the observations can be processed as a detailed spectrum, or the observations can be reduced to a collection of parameters before being used in the calculation. As a specific example, the spectrum can be simply reduced to a collection of values that identify the wavelength and height of one or more peaks in the spectrum.

At S14, a "model recipe" is established that defines a parametric model of the target structure based on a number of parameters p _i (p ₁ , p ₂ , p _{3 ,} etc.). In a 1-D periodic structure, such parameters may represent, for example, the angle of the sidewall, the height or depth of the feature, and the width of the feature. The properties of the target material and the underlying layer are also represented by parameters such as the refractive index (at a particular wavelength present in the detected radiation beam). Importantly, although the target structure can be defined by many parameters describing its shape and material properties, for the purposes of the following program steps, the model recipe will define many of these parameters with fixed values, while others will be variable. Or "floating" parameters. For the purposes of describing Figure 4, only the variable parameters are considered to be the parameters p _i . The variable parameters will typically include the parameters of interest (the attributes to be measured) and the so-called "obstructive" parameters. These parameters are parameters related to the parameter of interest and may also affect the observed spectrum. In the prior art, for example in US20120123748, a selection of automated methods for selecting fixed and floating parameters is described.

In general, it is assumed that the parameters of the structural model (even variable parameters) do not change throughout the exposure process using the detected radiation. On the other hand, this assumption may not be effective in all situations in accordance with the principles of the present invention. Modifications of the method will be further discussed below, taking into account changes in parameters during exposure. The conventional steps of the method will first be described.

At S15, the model target shape is estimated by setting an initial value p _i (0) for the floating parameter (ie, p ₁ (0), p ₂ (0), p ₃ (0), etc.). Each floating parameter can be generated with certain constraints as defined in the recipe.

At S16, parameters that represent the estimated shape along with the properties of the different materials in the model are used to calculate the scattering properties, for example, using the rigorous optical diffraction method described in the prior art or other solvers of Maxwell's equations. This calculation gives an estimate or model spectrum of the estimated target shape for a given combination of wavelength, polarization, angular distribution, and the like.

At S17 and S18, the measured spectrum and the model spectrum are then compared, and the similarity and difference between the measured spectrum and the model spectrum are used to calculate a "quality function" for the shape of the model target.

Assuming that the quality function indicates that the model needs to be improved before the model accurately represents the actual target shape, control passes to step S19, in which new parameters p ₁ (1), p ₂ (1), p ₃ (1), etc. are estimated and The new parameters are repeatedly fed back to step S16. Steps S16 to S18 are repeated. To aid in the search, the calculation in step S16 further produces a partial derivative of the quality function, which in the particular region of the parameter space indicates that increasing or decreasing the parameter will increase or decrease the sensitivity of the quality function. The calculation of the quality function and the use of the derivative are generally known in the art and will not be described in detail herein.

When the quality function indicates that the repeated program has converge to a solution with the desired accuracy, control passes to step S20, and the current estimated parameter (e.g., CD value) is reported as the measurement of the actual target structure.

Once the value for one target has been calculated, the new target on the same substrate or similar substrate can be measured using the same step S13 or the like without changing the measurement recipe. In the case where different types of substrates or targets are to be measured, or in any situation where it is necessary to change the measurement recipe, control is instead transferred to step S11 or S12.

Figure 11 illustrates any of the methods of applying a metrology method (e.g., Figures 2 through 10) in the management of a lithography manufacturing system. The steps will be listed here and then explained in more detail:

S21: processing the wafer to create a structure on the substrate

S22: Measuring CD and/or other parameters across the substrate

S23: Update the weights and measures formula

S24: Update lithography and / or program recipes

At step S21, a structure is created across the substrate using a lithography manufacturing system. At S22, a metrology device 240 having a first, second detection system, etc., is used to measure the properties of the structure across the substrate. At step S23, the metrology recipe and calibration of the EUV metrology device 244 and/or other metrology device 240 are updated, as appropriate, in view of the obtained measurement results. For example, where the EUV metrology device 244 has a lower yield than the optical metrology device 240, some accurate measurements using EUV radiation can be used to measure the use of optical metrology devices for specific substrate designs and procedures. Calculation.

At step S24, the measured values of the CD or other parameters are compared to the desired values, and the measurements of the CD or other parameters are used to update the settings of the lithography apparatus and/or other devices within the lithography manufacturing system. By providing an EUV metrology device as part of a metrology system, yield and/or accuracy can be improved and the performance of the entire lithography production facility can be improved. Even at the smallest technology node, product features and/or product-like features can be measured directly, and intra-grain targets can be provided and measured without losing too much area.

In the above steps, it is assumed that measuring a sufficient target across a substrate and across multiple substrates allows a statistically reliable model of the program to be derived. It is not necessary to fully express the profile of the CD and other parameters as a change across the substrate. For example, the cross-section of CD and other parameters can be expressed as an intra-field profile and a repeated overlay field common to all fields (each of which is patterned using patterned device MA at different locations on substrate W). Low-order inter-field variation of internal variation. The setting of the lithography program adjusted in step S24 may include an in-field setting and an inter-field setting. These settings can be applied to all operations of the device or to a particular product layer.

in conclusion

The techniques disclosed herein allow for information on the increase in structure of interest without necessarily inferring separate measurement steps and separate illumination systems. In particular, the spectrum or other information about the second band can be obtained simultaneously or sequentially using "residual" radiation from the first detection system operating in the first band.

Although specific examples of the methods and apparatus have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The design of the metrology device is free to select the number of configurations of different bands and detection systems to achieve the desired functionality within the constraints of space and cost. The method of measuring the shape and material of the structure from the detected signal can also be freely selected from a wide variety of available techniques, whether known in the art or in the future.

The term "lens", as the context of the context allows, can refer to any or a combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components.

Further embodiments in accordance with the present invention are provided in the following numbered items:

CLAIMS 1. A metrology apparatus for measuring an attribute of a structure, the weighting apparatus comprising: an illumination system for irradiating the structure with radiation; a first detection system comprising a first spectral grating and a first detector, the first spectral grating configured to receive the radiation after interacting with the structure, the first detector configured to receive one of the first spectral grating diffractions or a plurality of higher order radiation to detect a spectrum in a first band; a second detection system configured to receive at least a portion of the zero order radiation reflected by the first spectral grating and to analyze one or more other This zero-order radiation in the band.

2. The metrology apparatus of clause 1, wherein the second detection system comprises a second spectral grating and a second detector, the second spectral grating configured to receive the zero order radiation from the first spectral grating The second detector is configured to detect a spectrum in a second band by receiving one or more higher order radiations that are diffracted by the second spectral grating.

3. The metrology apparatus of clause 1 or 2, wherein the second detection system comprises a polarization analyzer, the second detector configured to receive radiation in the second wavelength band selected by polarization.

4. The metrology apparatus of any preceding clause, wherein the first waveband comprises a wavelength in the range of from 1 nanometer to 100 nanometers and the second wavelengthband comprises a wavelength longer than 100 nanometers.

5. The metrology apparatus of clause 4, wherein the second wavelength band comprises a wavelength longer than 300 nanometers.

6. The metrology apparatus of clause 4, wherein the second wavelength band comprises a wavelength shorter than 300 nanometers.

7. The metrology apparatus of any preceding clause, wherein in operation, the first detection system is housed in a low pressure environment and the second detection system is housed in an environment substantially at atmospheric pressure.

8. The metrology apparatus of any preceding clause, wherein the second detection system is further configured to divide the zero order in one or more of the bands other than the first band and the second band At least a portion of the radiation is directed to a third detection system configured to analyze the radiation in a third band.

9. The metrology apparatus of clause 8, wherein the second detection system comprises a second spectral grating, and wherein the portion of the radiation directed to the third detection system comprises a zero order reflected by the second spectral grating At least part of the radiation.

10. The metrology apparatus of clause 8 or 9, wherein the third detection system comprises a third spectral grating and a third detector, the third detector configured to receive by the third spectrum The grating diffracts one or more high order radiation to detect a spectrum in a third band.

11. The metrology system of clause 8, 9 or 10, wherein the third detection system comprises a polarization analyzer, the third detector configured to receive the third wavelength band selected by polarization radiation.

12. The metrology apparatus of any one of clauses 8 to 11, wherein the first wavelength band comprises a wavelength in the range of 1 nm to 100 nm, and the second wave band comprises a wavelength longer than 100 nm. .

13. The metrology apparatus of clause 12, wherein the third wavelength band comprises a wavelength longer than 300 nanometers.

14. The metrology apparatus of clause 12 or 13, wherein the second wavelength band comprises a wavelength shorter than 300 nanometers.

15. The metrology apparatus of any of clauses 8 to 14, wherein in operation at least the first detection system is housed in a low pressure environment and the third detection system is substantially contained at atmospheric pressure.

16. The metrology apparatus of any preceding clause, further comprising a processing system for determining a property of the structure using the first analysis data received from the first detection system.

17. The metrology apparatus of clause 16, wherein the processing system is further configured to determine the attribute using the second analysis data received from the second detection system in conjunction with the first analysis data.

18. The metrology apparatus of clause 16, wherein the processing system is further configured to determine the attribute using the third analysis data received from the third detection system in conjunction with the first analysis data or the second analysis data.

19. The metrology apparatus of any of clauses 8 to 15, further comprising a processing system that uses one or more of the following to determine an attribute of the structure: from the a first analysis data received by the detection system, a second analysis data received from the second detection system, and a third analysis data received from the third detection system.

20. The metrology apparatus of any preceding clause, further comprising a radiation source for providing radiation in the first waveband and the second wavelengthband to the illumination system.

21. The metrology apparatus of clause 20, wherein the radiation source is a broadband radiation source operable to simultaneously generate radiation in the first waveband and the second wavelengthband.

22. The metrology apparatus of clause 20 or 21, wherein the radiation source is operable to generate a small Radiation in a waveband in the range of 100 nanometers to more than 400 nanometers.

23. The metrology apparatus of clause 22, wherein the radiation source is operable to generate radiation in a waveband in a range of less than 10 nanometers to more than 400 nanometers.

24. The metrology apparatus of any preceding clause, wherein the first source of radiation is a source of higher order harmonic generators.

25. A method of measuring an attribute of a structure by a lithography process, the method comprising the steps of: (a) applying radiation comprising a first band and a second band of radiation. Radiation to irradiate the structure; (b) directing at least a portion of the radiation after interaction with the structure to a first spectral grating; (c) using one or more higher orders of diffraction from the first spectral grating Radiation detects a spectrum in a first band; (d) analyzes at least a portion of the zero-order radiation reflected by the first spectral grating in the second band.

26. The method of clause 25, wherein the step (d) comprises: (d1) directing at least a portion of the zero-order radiation after interaction with the structure to a second spectral grating; and (d2) using The second spectral grating diffracts one or more higher order radiations to detect a spectrum in the second wavelength band.

27. The method of clause 26, wherein the radiation in step (a) comprises radiation in a third band, the method further comprising the step of: (e) analyzing the third band At least one of zero-order radiation reflected by the two-spectrum grating section.

28. A method of fabricating a device, comprising: transferring a pattern from a patterned device to a substrate using a lithography process, the pattern defining at least one structure; measuring one or more attributes of the structure for use in determining And calibrating a value of one or more parameters of the lithography program; and applying a correction to the subsequent operation of the lithography program based on the measured property, wherein the step of measuring the attributes of the structure includes using The metrology apparatus of any one of clauses 1 to 24 measures an attribute.

29. The device manufacturing method of clause 28, wherein the functional device pattern defines a product feature having a critical dimension of less than 50 nanometers, optionally less than 20 nanometers.

30. A device fabrication method comprising: transferring a pattern from a patterned device to a substrate using a lithography process, the pattern defining at least one structure; measuring one or more attributes of the structure for use in determining And calibrating a value of one or more parameters of the lithography program; and applying a correction to the subsequent operation of the lithography program based on the measured property, wherein the step of measuring the attributes of the structure includes using The method of any one of clauses 25 to 27 measures an attribute.

The foregoing description of the specific embodiments of the present invention will fully disclose the general nature of the invention, and the invention can be easily modified for various applications by the knowledge of the skill of the art without departing from the general inventive concept. And/or adapting such specific embodiments without undue experimentation. Therefore, based on the teachings and guidance presented in this article, such adjustments and modifications It is intended to be within the meaning and scope of the equivalents of the disclosed embodiments. It is understood that the phraseology or terminology herein is used for the purposes of the description

The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but only by the scope of the following claims and their equivalents.

Claims (15)

A metrology apparatus for measuring a property of a structure, the metrology apparatus comprising: an illumination system for irradiating the structure with radiation; a first detection system, A first spectral grating is included and the first detector is configured to receive the radiation after interacting with the structure, the first detector configured to receive Detecting, by the first spectral grating, one or more high-order radiations to detect a spectrum in a first wavelength band; a second detection system configured to receive a zero-order reflected by the first spectral grating At least a portion of the radiation and analyzing the zero-order radiation in one or more other bands. The weighting device of claim 1, wherein the second detecting system comprises a second spectral grating and a second detector, the second spectral grating configured to receive the zero-order radiation from the first spectral grating, The second detector is configured to detect a spectrum in a second band by receiving one or more higher order radiations that are diffracted by the second spectral grating. The metrology apparatus of claim 1 or 2, wherein the second detection system comprises a polarization analyzer configured to receive radiation in the second wavelength band selected by polarization. A metrology apparatus according to claim 1 or 2, wherein the first wavelength band comprises a wavelength in the range of 1 nm to 100 nm, and the second wave band comprises a wavelength longer than 100 nm. The metrology apparatus of claim 4, wherein the second wavelength band comprises a wavelength longer than 300 nanometers. The metrology apparatus of claim 4, wherein the second wavelength band comprises a wavelength shorter than 300 nanometers. The metrology apparatus of claim 1 or 2, wherein in operation, the first detection system is housed in a low pressure environment and the second detection system is housed in an environment substantially at atmospheric pressure. The metrology apparatus of claim 1 or 2, wherein the second detection system is further configured to transmit the zero-order radiation in one or more bands other than the first band and the second band At least a portion is directed to a third detection system configured to analyze radiation in a third band. The metrology apparatus of claim 8, wherein the second detection system comprises a second spectral grating, and wherein the portion of the radiation directed to the third detection system comprises zero-order radiation reflected by the second spectral grating At least part. The metrology apparatus of claim 8, wherein the third detection system comprises a third spectral grating and a third detector, the third detector configured to receive diffraction by the third spectral grating One or more higher order radiations to detect a spectrum in a third band. The metrology apparatus of claim 8, wherein the third detection system comprises a polarization analyzer, The third detector is configured to receive radiation in the third band selected by polarization. The metrology device of claim 8, wherein the first band comprises a wavelength in the range of 1 nm to 100 nm, and the second band comprises a wavelength longer than 100 nm. The metrology apparatus of claim 12, wherein the third wavelength band comprises a wavelength longer than 300 nanometers. The metrology device of claim 12, wherein the second wavelength band comprises a wavelength shorter than 300 nanometers. The metrology apparatus of claim 8, wherein in operation, at least the first detection system is housed in a low pressure environment, and the third detection system is substantially accommodated at atmospheric pressure.